I have an old thermostat like those round types but mine is square type. My question is how do I get the 18 or 24 volts on it so I can use the thermostat when the power gose off.. I have a Gas floor furnace and The thermostat will not work when the power is off is there any way I can jump it some how when the power is off to make the thermostat kick my furnace on thanks a lot

No your system needs the 24 volts for its operation. If you can find another sourse of 24 volts during a power failure then it might work.